The present invention relates to tracking the status of a lock in general, and to providing an indication of the status of a lock being either locked or unlocked, in particular.
Quite often, people forget whether they have locked the door in the house, office, or other premises, or not. As a common occurrence—someone may depart a building intending to secure it by externally locking a certain door using its corresponding key, upon departure. However, following his departure, he or she may be unable to recall whether or not they have actually locked the door, securing it by turning the corresponding key into a locked position. Hence, there is a need to provide a reliable, low-cost, convenient device which may be attached to the majority of portable keys, which device shall clearly indicate whether the lock corresponding to said key has been actuated into the lock position or not.
Several inventors have suggested various devices including attachments to standard keys, which would hopefully indicate the most recent lock position. However, most of these inventions rely on the user exerting a force on the attachment housing, using his fingers while turning the key in the clockwise or counter-clockwise direction. This force, or rotational torque, has been suggested to activate an array of mechanical and/or electronic switching devices which in turn were conceived as leading to the sought after locked indication. (See, for example, U.S. Pat. No. 4,440,011 by Klein, and/or US Patent Application 20090201151 of 13 Aug. 2009 by Yosef De Levie et al.) Certain inventions even indicated a specific location on said attachment in which the user's thumb and/or finger were to be positioned. Many keys are inserted into the lock in a horizontal position i.e. the key head is parallel to the floor, such that a thumb-activated switch may be difficult to achieve. Furthermore, occasional contact of keys including said attachments with various external objects, e.g.—coins or other objects in a user pockets, may reset the memory/indicator into an erroneous position. Moreover, several users may have different physiological structures of hands and fingers resulting in a great variety of forces being applied to the key while rotated inside the lock, which may lead to errors in the indicator output.